Transthoracic echocardiography (TTE) is recommended in patients with ischemic stroke when cardiac etiology is suspected to help plan secondary stroke management. However, discrepancy for specific clinical recommendation exists between cardiologists and neurologists, and data evaluating usefulness of TTE in unselected patients with cryptogenic strokes (CS) and embolic strokes of undetermined source (ESUS) are lacking. The investigators sought to evaluate the value of routinely performed echocardiography in consecutive CS/ESUS patients. The investigators will perform TTE as recommended by guidelines including agitated saline contrast and speckle-tracking to investigate potential implications for secondary stroke management. In addition, the researchers aim to evaluate the effectiveness of long-term continuous electrocardiogram (cECG) monitorering with newer Holter monitors to detect cardiac arrhythmia in patients with CS/ESUS.

In this prospective study, the investigators aim to evaluate 500 consecutive patients, regardless of age, in sinus rhythm with acute IS and potential cardioembolic stroke (CES) or cryptogenic stroke (CS/ESUS) according to Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. Strokes are determined by magnetic resonance imaging. The researchers will perform TTE as recommended by guidelines including agitated saline contrast and speckle-tracking to investigate potential implications for secondary stroke management.

The investigators aim to explore underlying heart conditions and comorbidities among CES and ESUS patients. Data will include left atrium morphology, atrial septal aneurysm, valvular disease, mural thrombus and patent foramen ovale (PFO). Focus will be analysis of data on older patients, as some studies indicate that in ESUS patients >60 years of age, there is a higher prevalence of PFO in patients with low atherosclerosis and cardioembolic risk.

This project can potentially guide cardiologists and neurologists, on common grounds, for stroke management of potential cardioembolic origin. Implications of referring all-comers with stroke of potential cardioembolic origin to echocardiography will be illustrated.

Inclusion Criteria:

• Hospitalized patients with verified acute ischemic stroke determined by magnetic resonance imaging (MRI) and/or computed tomography (CT) of cerebrum.
• Patients, regardless of age, in sinus rhythm with acute IS and potential cardioembolic stroke or cryptogenic stroke (CS/ESUS) according to Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria.

Exclusion Criteria:

• Persons not able to cooperate.
• Persons unable to understand and sign "informed concent."

All hospitalized patients with acute ischemic stroke from department of neurology (stroke unit) in University of Copenhagen Herlev Hospital.